How much blow by is normal? I have enough to make a mess of the underside of the backhoe coming out of a vent tube off the side of the crankcase. It is a 1991 Case 580K with a natural aspirated 390 CI 4 cylinder. Starts and runs great. Hasn’t been using much oil up till now. It’s due for an oil change soon.
Blow-by is measured by a gauge--inches of water. But some engine manufactures don't list a value. Just how bad is the cloud? And how many engine hours does it have?
There isn’t a cloud. Just dripping oil. The engine hour meter has been disconnected since I’ve had it. You don’t want to open the fill cap with the engine running or you will get sprayed with oil droplets. If that gives you an idea of how much blow by.
Well, the best anyone can say is--the rings are probably worn out. It's all about compression leaking to crank case causing pressure.
Is there a pcv or anything that can be bad?
Time to do a compression test. Every engine I have seen that was blowing out the oil fill tube when it was removed had a hole in a piston.
And-----if that is the case, normally you can see it huff on compression stroke, visible to the {Old School Eyes}.
I bought another motor grader with a Cummings 4bt in it. When it is running, it will spert a little bit of oil out the fill tube if the cap is off. Does not smoke once warm but does when you first start it. Seller claims smaller diesels do that. My other machine does not. I got a 5k discount on the purchase because of that. What do you guys think about a small amount of blow by. More than likely, this machine has sat for a while because it does not look like it was used much. My other machine has much more wear in the assemblies. I bought it as a spare for parts but it looks good enough that it could be set up to run as a second. Not sure if i should get into the engine or not
Could have sat for so long, the liners are pitted and the rings screwed up. As long as it stays running for what you want, everything is good. We ain’t running Lambo’s here.
Oh no--time to reach under the mattress and spend a bunch of frog hides.
Alright what the hell is a frog hide? Or better yet why do you call money that
Frog hides and Lambo’s go hand in hand and then out the door, never to be seen again. Lol
Because from a distance it looks like dollar bills only with legs.
Supid question time. How do you do it on a diesel? No spark plugs
No question is stupid in my world. The injectors need to be removed and then a compression tester that has the correct fittings for a Cummins 390 is needed. There should be a lot of information on web (YouTube) on how to do it. Harbor Freight may have a test kit. I never have looked.
I was afraid of that but didn’t know. You know I never suspected low compression because of the way it fires off on the first crank. Also there’s no puffing or excessive smoke. What should you be seeing from a good engine in respect to the fill tube blowing out oil? Does a new engine have any blow by? I guess I’l get out the service manual and read up on injector removal.
Being a Case/Cummins there is probably a crankcase pressure spec and procedure in the Cummins manual.
Cummins measures their base pressure specs with a blowby orifice tool with a .221" (15/64-in) outlet. Or, make your own and hook your manometer, if you are curious . 126 L/Min(10.5"rise) @ 2200rpm 152 L/Min(14.5"rise) @ 2500rpm 170 L/Min(17"rise) @ 2800 rpm
.22 LR shell with the end cut off could be the start of a redneck orifice?
Good answer, Good answer. I like the way you think. I’m going to be watching you.,…. Or, a Remington .221 Fireball. That’s a blast from the past. Anyone remember that round?
Or a .22 jet
Or bypass all that and find a retired {old fart} diesel mechanic to take a quick old school look and tell you straight up--it has issues. Lots of old boomer mechanics around just looking for something to do so can hide from the wife for a few hours.
Can't a plugged crankcase breather cause excess blow by?
Yes it can, but I think in this case with a open draft tube leaving a oil on the ground that's most likely not a issue. When breathers plug {normally} as pressure builds the pressure has to go some where and in some cases it starts pushing oil past front and rear crank seals, valve cover gaskets, timing cover gaskets & straight up out the dip stick tube. * With modern engines {I will use the ISX/X15 as an example} that have a computer monitored closed type system. Those have a rather large breather return filter. I have run into a situation of some plugged with sludge that put it in derate mode and or completely shut engine down. And I didn't have a filter on hand to replace with, and those are made with a sealing edge to it's housing. So I used everyone's favorite Bob Vila tool the battery powered drill and bored 1/2 holes through a area of filter, reinstalled, pressure was then vented to it's draft tube and no more issue till I could get a filter.
I have the crank vent on my 7.3L Ford running down to the frame behind the cab. It's got near 10k hours, has some blowby when hot. Nothing crazy, but more thn none for sure. Pulled up to the drive-thru and a small like 2ft around cloud rolled up from under the truck. Breeze was blowing a bit i guess. Dude instantly closed the window and acted like it was a cloud of poison gas. May route it back into the turbo, it's gotten customers or random people at lights all nervous. Is your truck on fire?
A good example of a hard breathing engine even in good condition is the 3406's. As soon as they go to work the breathing lessens.
My old man said he put a fitting in the exhaust pipe and connected the blowby hose into the exhaust on his 3406A powered KW because he was sick of it leaving stains on the driveway.
On a pickup would need to be after the muffler at minimum. And even then I'd worry the exhaust pressure is higher than crank pressure. Stock it was hooked in the intake a bit before the turbo. It was oiling all that and i.was concerned it potentially could run away if the blowby got real strong. Like engine WOT pulling it's guts out like mine does often hauling 2 cords of firewood.
Is that the meter that shows how manly you are?
Yes'm it tells you if your balls to the wall or not.